1. Field of Invention
The present invention relates to a plane light source device. More particularly, the present invention relates to a backlight module.
2. Description of Related Art
FIG. 1A is a schematic diagram of a conventional backlight module, and FIG. 1B is a top view of the backlight module of FIG. 1A. Referring to FIGS. 1A and 1B, a plurality of light source sets 120 is disposed on a bottom 112 of a light box 110 of a conventional backlight module 100. Each of the light source sets 120 includes a substrate 122 and a plurality of light-emitting diodes (LEDs) 124 disposed on the substrate 122. In the backlight module 100, the heat generated by the LEDs 124 is conducted to the bottom 112 of the light box 110 via the substrate 122. Conventionally, a fan 130 is used to generate a forced convection to reduce the temperature at the bottom 112 of the light box 110, so as to achieve the purpose of heat dissipation.
However, the air flow generated by the conventional fan 130 is capable of effectively reducing the temperature of a portion of the bottom 112 of the light box 110 near the fan 130 only, so the temperature of the rest portion of the bottom 112 of the light box 110 far away from the fan 130 is still quite high. In other words, the air flow generated by the fan 130 cannot effectively dissipate the heat of the entire bottom 112 of the light box 110, and the temperature at the bottom 112 of the light box 110 is not uniform. In addition, as the air flow generated by the fan 130 only reduces the temperature of a portion of the bottom 112 near the fan 130, a portion of the heat generated by the LEDs 124 cannot be effectively conducted to the external environment with the air flow generated by the fan 130 after being conducted to the bottom 112 of the light box 110. Therefore, the heat dissipation efficiency of the backlight module 100 is unsatisfactory, so the luminance of the LEDs 124 declines as the temperature increases, and color shift will occur as well. In another aspect, if the temperature difference of the LEDs in the entire backlight module is over high, the problem of uneven luminance will also occur.